Sponge



FIG. 1 is a perspective view showing the new design for a sponge;

FIG. 2 is a front view thereof, a rear view being a mirror image thereof;

FIG. 3 is a right side view thereof, a left side view being a mirror image thereof;

FIG. 4 is a top view thereof; and,

FIG. 5 is a bottom view thereof.

The portions of the sponge in FIGS. 1-3 and 5 shown in broken lines are included to show features that form no part of the claimed design. In addition, the dot-dash-dot type broken lines shown in the drawing views define the boundaries of the claimed design and form no part of the claimed design. 

CLAIM The ornamental design for a sponge, as shown and described. 